Many cruise lines do block cabins for groups and McKeever is correct normally low - mid range cabins.

However,with Regent they do not normally hold blocks of space for groups without a full deposit on each cabin.

The suites that sell the fastest on a ship are the upper level and lowest level suites.

On long voyages prime cabins (such as 601 and big suites) are often not for sale on segment cruises but held for people doing the entire voyage.